This invention relates to vibrating screens and more particularly to variably sloped vibrating screens.
The aggregate industry utilizes many styles of screen machines to sort aggregates by size. Most screen machines utilize vibration to agitate the mixture of aggregates to promote separation through various sized openings in the screening surfaces. Sorting is achieved by undersized particles passing through the openings in the screening surface and the oversized particles being retained above the screen surface. These machines usually have some type of vibrating mechanism to shake the unit and its screening surfaces. The vibrating mechanisms usually include an unbalanced weight mounted on one or several rotating shafts which when rotated, force a cycling motion into the screen machine.
Sometimes a screen is designed to be oriented in various sloped positions. This is frequently found in portable equipment that requires a lower profile for travel, as well as multiple sloped positions as needed for various screening applications.
Often material dumped into the feed end of a conveyor will contain a large amount of fine material (sand, dirt, small stones, etc) which will pass very quickly through all of the decks of the vibrating screen. The majority of this material will fall through the first 4 feet to 5 feet length of the screen. Typically, it will fall into the underscreen discharge conveyor, making that an undesirable product. Some prior art systems have used a difficult-to-adjust, conveyor which mounts above the existing underscreen conveyor and is short and extends part way inside the underscreen hopper under the intake end of the screen.
Consequently, there is a need for improvement in sorting systems for variable slope vibrating screens which removes a percentage of fines from the final product.